Hybrid electric vehicles (HEVs) differ from conventional motor vehicles in that they typically employ an electric machine in addition to an internal combustion engine (ICE) in order to provide traction to drive the vehicle. HEVs are also typically equipped with a battery for storing electrical power for powering the electric machine.
In some HEVs the electric machine may also be employed as a generator that is powered by the internal combustion engine in order to generate electrical power to charge the battery.
It will be appreciated that HEVs represent a complex system the control of which is a non-trivial task. Considerable efforts have been made to develop controllers for HEVs that reduce the consumption of fuel by the ICE during the course of a given drive cycle.